Dolby Digital (AC3) can output 6.1 channels thru matrix decoding of Dolby Digital EX streams. There's a free encoder, Aften, which has the feature of setting the EX flag if you want to use it.Dolby Digital Plus (EAC3) supports 8 channels but I don't think it's being used in movies. Also no free encoder available.Dolby TrueHD also supports up to 8 discrete channels but it's also not used in movies (only 6 channels is used) and there's no option to encode anything in this format as the only encoder available is the same as for Plus, it's called Dolby Media Encoder, it only runs in a Mac and costs U$S 8.000 (I kid you not, 8.000 dollars!).

There are several options to decode Dolby streams.For Dolby Digital (6 channels) you can use these, some are Directshow decoders:- AC3filter, which only supports 6 channels of output- ffdshow, which supports up to 8 channels of output but doesn't do EX decoding, just matrixing- Media Player Classic Home Cinema or MPC-HC has its own Directshow decoder- any directshow based decoder from software DVD players that can be used within other directshow player (ie: using cyberlink's decoder in MPC or bsplayer or kmplayer, etc)- VLC player which uses its own decoders (not Directshow based)- Mplayer (not directshos based)For Dolby TrueHD- ffdshow- any directshow based decoder from software DVD players that can be used within other directshow player (ie: using cyberlink's decoder in MPC orFor Dolby Digital Plus- ffdshow- any directshow based decoder from software DVD players that can be used within other directshow player (ie: using cyberlink's decoder in MPC or

AC3filter, ffdshow, VLC, MPC-HC and Mplayer and are free. For ffdshow, get the latest "nightly build" ones because the stable ones might not have TrueHD or Plus support.I hope this helps.This is a very basic question, so you might wanna head to forum.doom9.org and check out the Audio FAQ in the Audio subforum where you might find the answers to many questions.http://forum.doom9.org/showthread.php?s=&a...8300#post424067

Dolby Digital (AC3) can output 6.1 channels thru matrix decoding of Dolby Digital EX streams. There's a free encoder, Aften, which has the feature of setting the EX flag if you want to use it.

Small addition: Legacy DD will not decode to 6.1 channels, it is and will be 5.1. Feeding it with DD-EX streams won't causeno harm but will not result in 6.1 channels. A DD-EX decoder will produce the 6.1 channels ... so far for the stuff from Dolby.A kind of selfmade DD-EX decoder would be the combination you mentioned: use the surround channels (LS/RS) of aDD decoder and feed it into a ProLogic decoder set to 3-stereo (L,C,R output)...that way you'll get the back-center channel.Tried once with a receiver combination, worked suprisingly well..:-)